Temperature-compensated clamp seal



1966 J. R. ABBOTT 3,266,006

TEMPERATURE- COMPENSATED CLAMP SEAL Filed Feb. 12, 19 62 JbA/N 12- A BBOTT IN VEN TOR.

ATTOQN EYS United States Patent 3,266,006 TEMPERATURE-COMPENSATED CLAMP SEAL John R. Abbott, Sherman Oaks, Calif., assignor-to Gray & Huleguard, Inc., Santa Monica, Calif., a corporation of California Filed Feb. 12, 1962, Ser. No. 172,665 4 Claims. (Cl. 339-60) This invention relates generally to temperature compensation of interfitting bodies, and more particularly has to do with preventing undesirable variation of clamping force transmission between .interfitting members when subjected to temperature change, the members having different temperature coeflicients of expansion.

When coaxial members having different temperature coefiicients are clamped together at an axially tapering interface, the clamping force transmission will in general vary with temperature. This may be considered to result from the fact that the radial components of the clamping force are directly affected by unequal. growth or shrinkage of the clamped members. In addition, axial components of the clamping force may be affected in like manner. the interface is used as a fluid seal, leakage of the seal developing when the clamping force transmissions drops below the fluid pressure acting at the seal, in response to temperature change. Accordingly, a need exists for a mechanism characterized in that relative thermal expansion and contraction of members clamped together at a tapered interface will not result in appreciable variation of the clamping force transmission at the interface.

The present invention meets this need, and may be considered as solving the referred to problem, through the provision of a novel clamp assembly broadly comprised of substantially coaxial members clamped together at first and second coaxial interfaces having apices proximate the same location, typically on the member common axis. Typically, the interfaces are re-entrant and taper axially oppositely with equal ia-ngularity. Thus, when an outer tubular member is made to comprise metal such as steel and an inner member to comprise hardened plastic such as molded tetrafiuoroethylene, temperature variation will not appreciably affect the clamping force transmission at the re-entrant interfaces.

Additional objects of the invention include the provision of a novel electrical connector incorporating the invention, as well as a novel bearing incorporating the invention.

These and other objects and advantages of the invention, as Well as the details of an illustrative embodiment,

Serious problems can arise as for example where will be more fully understood from the following detailed description of the drawings, in which:

FIG. 1 is a cross section through an electrical connector incorporating the inveniton; and

FIG. 2 is a cross section through a bearing assembly incorporating the invention.

Referring first to FIG. 1, the novel electrical connector is shown to include a receptacle means generally desig nated at 10 and a plug means generally designated at 11 as being electrical-1y and mechanically connected with the receptacle means.

The receptacle means is shown to include a tubular housing 12 containing an insert member 13, which in turn contains a multiplicity of pins 14 the terminals of which project at 15 from the end face 16 of the insert. Typically, the insert may be formed of the hardened thermosetting plastic material such as molded tetrafluoroethylene. The circular cross section insert is longitudinally or axially grooved at 17 for the reception of the head of a key 18 the remainder of which is carried by a tubular retainer 19 which is received over the terminal end of ice the insert. The retainer is externally and circularly flanged at 20 to carry a nut member 21 which has threaded connection to the receptacle 12 at 21.

The projected skirt portion 22 of the retainer 19 fits concentrically bet-ween plug members 23 and 24, the latter having thread connection with the skirt portion at the location 25. The inner member 23 is typically keyed to the skirt portion at the location 26 to accommodate relative axial sliding therebetween but resisting turning. This circumstance prevents turning of the socket insert 27 relative to the pin insert 13, whereby the multiple sockets 28 carried by the insert 27 may maintain registration with the pin terminals 15 during connection and disconnection of the plug and receptacle. Such connection is facilitated by turning of the outer plug member 24 on the skirt portion 22 of the retainer 19. It will also be noted that the socket insert 27 is keyed at 29 to the plug member 23. When the plug and receptacle are completely connected as illustrated, the face 16 of the receptacle insert 13 and the face 30 of the plug or skirt insert 27 have frusto-conical interengagement at the locations 31 about the pin terminals 15, thereby to form a sealing relationship sealing otf access of fluid to the pin terminals.

Such access of fluid to the space about the receptacle or pin insert 13 is prevented in the first instance by the seal effected by the temperature compensated clamp assembly which will now be described, this assembly being an important feature of the invention. The assembly may be considered to comprise substantially coaxial members such as members 19, 12 and 13, which are clamped together at first and second substantially frustoconical interfaces, as for example are designated at 32 and 33. These interfaces are characterized as having apices falling proximate the same location as for example is shown at 34 on the common axis of the members. The interfaces 3-2 and 33 may be further characterized as being re-entrant as illustrated, as tapering axially oppositely, and as having substantially equl taper angularity. It is chracteristic of this phase of the invention that relative thermal expansion and contraction of the members which are clamped together at the interfaces will not result in appreciable variation of the clamping force transmitted at the interfaces, in spite of the fact that the members have different thermal coefficients of expansion. Accordingly, should fluid gain entrance or access from the exterior past the thread 21 and to the annular gap 3 5 surrounding the flanged section 36 of the insert 13 such fluid will not be able to pass the seal effected at the clamped together interface locations 32 and 33 in spite of Wide temperature changes, provided that suflicient clamping pressure is developed at the interfaces when the plug and receptacle are assembled. Specifically, the nut member 21 may be tightened on the receptacle housing 12 to develop the required sealing pressure. As previously mentioned the insert may comprise a hardened plastic material such as tetrafluoroethylene and the members 19 and 12 may comprise metal such as steel.

Referring now to FIG. 2 a ball bearing is shown at 40 with the inner race 41 thereof mounted on a shaft 42, and the outer race 43 thereof carried by the bore 44 of a support member 45. The latter is typically annular and may have a shoulder 46 for locking the outer race of the bearing as illustrated.

The support 45 is shown as clamped between members 47 and 48 and specifically at the interfaces 49 and 50, these being substantially frusto-conical and having apices proximate the same location such as is shown at 51 on the member common axis 52. Here again the interfaces 49 and 50 taper axially oppositely and have substantially equal taper angularity. However, the members 45, 47 and 48 may in general comprise materials having different thermal coeflicients of expansion, and as an example the members 45 and 47 may comprise steel, while the housing member 48 may comprise aluminum or an aluminum alloy. In this regard, the member 47 may be threaded into the housing member 48 as shown at 53.

It is again characteristic of the interfaces 49 and 50 that relative thermal expansion and contraction of the members 45, 47 and 48 will not result in appreciable variation of clamping force transmitted at the interfaces, and accordingly the support 45 will not become loosened due to temperature change. It is also seen that the gap 54 provided by the support 45 and the bore 55 of the housing member 48 allows for coaxial mismatch as between the housing 48 and the shaft 42. However, once the nut member 47 is tightened into the housing the bearing has fixed location and temperature change will not appreciably affect the clamping force transmitted at the interfaces 49 and 50.

I claim:

1. A temperature compensated clamp assembly including the combination of a plurality of coaxial members having different thermal coeflicients of expansion,

said members being clamped together at first and second re-entrant lfrusto-conical interfaces,

said first and second interfaces tapering axially oppositely and having apices proximate the same location on the axis whereby relative thermal expansion and contraction of said members will not result in apprecia'ble variation of the clamping force transmitted at said interfaces.

2. A temperature compensated clamp assembly including the combination of a plurality of coaxial members having different thermal coefiicients of expansion, said members being clamped together at first and second re-entrant frustro-conical interfaces, said first and second interfaces tapering in axially opposite directions at substantially equal angles and having apices proximate the same location on the axis whereby relative thermal expansion and contraction of said members will not result in appreciable variations of the clamping force transmitted at said interfaces. 3. A temperature compensated clamp assembly including the combination of a plurality of coaxial members having different thermal coefiicients of expansion,

of the clamping force transmitted at said interfaces, and

a gap at the periphery of a flanged section of said insert, said flanged section "being disposed between the first and second interfaces.

4. A temperature compensated clamp assembly including the combination of a plurality of coaxial members having different thermal coefiicients of expansion,

said members including a hardened plastic insert and tubular metallic bodies containing said insert,

an electrical terminal structure embedded in said insert,

said insert and said tubular bodies being clamped together at first and second re-entrant frustro-conical interfaces, and

a gap at the periphery of a flanged section of said insert, said flanged section being disposed between the first and second interfaces,

said first and second interfaces having apices proximate the same location on the member axis whereby relative thermal expansion and contraction of said members will not result in appreciable variations of the clamping force transmitted at said interfaces.

References Cited by the Examiner UNITED STATES PATENTS 2,419,018 4/1947 Gudie 339-89 X 2,454,838 11/1948 Richardson et al. 33994 X 2,860,316 11/1958 Watters et al. 339-94 X FOREIGN PATENTS 1,255,427 1/1961 France.

798,142 7/1958 Great Britain.

THOMAS J. HICKEY, Primary Examiner.

JOSEPH D. SEERS, Examiner.

A. S. TRASK, Assistant Examiner. 

1. A TEMPERATURE COMPENSATED CLAMP ASSEMBLY INCLUDING THE COMBINATION OF A PLURALITY OF COAXIAL MEMBERS HAVING DIFFERENT THERMAL COEFFICIENTS OF EXPANSION, SAID MEMBERS BEING CLAMPED TOGETHER AT FIRST AND SECOND RE-ENTRANT FRUSTO-CONICAL INTERFACES, SAID FIRST AND SECOND INTERFACES TAPERING AXIALLY OPPOSITELY AND HAVING APICES PROXIMATE THE SAME LOCATION ON THE AXIS WHEREBY RELATIVE THERMAL EXPANSION AND CONTRACTION OF SAID MEMBERS WILL NOT RESULT IN APPRECIABLE VARIATION OF THE CLAMPING FORCE TRANSMITTED AT SAID INTERFACES. 